/* Shared styles for all tools. Light and dark are both designed (not an
   automatic flip). Palette: cyan (interaction, "your result"), green (brand,
   links), subtle yellow (notes, "nearby"). Contrast ratios checked in both
   themes; see README. */

:root {
  color-scheme: light;
  --page: #f6f7f1;
  --surface: #fdfdf9;
  --surface-2: #f0f2ea;
  --ink: #10201c;
  --ink-2: #46544e;
  --muted: #66716b;
  --hairline: #dfe3da;
  --border: rgba(16, 32, 28, 0.12);
  --green: #1d7a4f;
  --green-ink: #17643f;
  --cyan: #0e98ad;
  --cyan-strong: #087a8c;
  --cyan-wash: #bfe3e6;
  --yellow: #d9a400;
  --yellow-wash: #f4e8bd;
  --note: #fbf4d6;
  --danger: #b4232f;
  --focus: #087a8c;
  --shadow: 0 1px 2px rgba(16, 32, 28, 0.06), 0 4px 16px rgba(16, 32, 28, 0.05);
  --radius: 14px;
  /* Fractions (categorical, validated all-pairs): sand ochre, silt slate blue, clay terracotta. */
  --sand: #b8860b;
  --silt: #5d7fc0;
  --clay: #a33d26;
  /* Texture groups, ordinal earthy ramp coarse -> fine (validated --ordinal),
     with the label ink that reaches 4.5:1 on each step. */
  --g1: #cfb070; --g2: #be975b; --g3: #ad7f48; --g4: #9c6737; --g5: #895028; --g6: #763a1c;
  --on-g1: #10201c; --on-g2: #10201c; --on-g3: #10201c; --on-g4: #ffffff; --on-g5: #ffffff; --on-g6: #ffffff;
  --mark: #0e98ad;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root:where(:not([data-theme="light"])) {
    color-scheme: dark;
    --page: #0d1412;
    --surface: #151d1b;
    --surface-2: #1d2724;
    --ink: #e9f1ec;
    --ink-2: #b9c6bf;
    --muted: #8d9993;
    --hairline: #2a3532;
    --border: rgba(255, 255, 255, 0.10);
    --green: #5cc994;
    --green-ink: #7fd8ab;
    --cyan: #1a9fb3;
    --cyan-strong: #4cc3d4;
    --cyan-wash: #17494f;
    --yellow: #b48d1f;
    --yellow-wash: #4b431c;
    --note: #2e2a17;
    --danger: #ff8f8f;
    --focus: #4cc3d4;
    --sand: #bb8c16;
    --silt: #6d8fd0;
    --clay: #c24a33;
    --g1: #624c23; --g2: #795c34; --g3: #916d46; --g4: #aa7e5a; --g5: #c3906f; --g6: #dca285;
    --on-g1: #ffffff; --on-g2: #ffffff; --on-g3: #ffffff; --on-g4: #10201c; --on-g5: #10201c; --on-g6: #10201c;
    --mark: #4cc3d4;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --page: #0d1412;
  --surface: #151d1b;
  --surface-2: #1d2724;
  --ink: #e9f1ec;
  --ink-2: #b9c6bf;
  --muted: #8d9993;
  --hairline: #2a3532;
  --border: rgba(255, 255, 255, 0.10);
  --green: #5cc994;
  --green-ink: #7fd8ab;
  --cyan: #1a9fb3;
  --cyan-strong: #4cc3d4;
  --cyan-wash: #17494f;
  --yellow: #b48d1f;
  --yellow-wash: #4b431c;
  --note: #2e2a17;
  --danger: #ff8f8f;
  --focus: #4cc3d4;
  --sand: #bb8c16;
  --silt: #6d8fd0;
  --clay: #c24a33;
  --g1: #624c23; --g2: #795c34; --g3: #916d46; --g4: #aa7e5a; --g5: #c3906f; --g6: #dca285;
  --on-g1: #ffffff; --on-g2: #ffffff; --on-g3: #ffffff; --on-g4: #10201c; --on-g5: #10201c; --on-g6: #10201c;
  --mark: #4cc3d4;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font: 16px/1.55 var(--font);
  color: var(--ink);
  background: var(--page);
}
a { color: var(--green-ink); text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: 4px; }
h1, h2, h3 { line-height: 1.2; margin: 0 0 0.4em; }
h1 { font-size: clamp(1.5rem, 1.1rem + 1.6vw, 2.1rem); letter-spacing: -0.01em; }
h2 { font-size: 1.25rem; }
h3 { font-size: 1.05rem; }
p { margin: 0 0 0.8em; }
small, .small { font-size: 0.875rem; }
.muted { color: var(--ink-2); }
.visually-hidden {
  position: absolute !important; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap;
}

/* Header */
.site-header {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  max-width: 1180px; margin: 0 auto; padding: 10px 20px;
}
.brand {
  display: inline-flex; align-items: center; gap: 10px;
  font-weight: 650; color: var(--ink); text-decoration: none; margin-right: auto;
}
.brand svg { flex: none; }
.header-tools { display: flex; gap: 8px; align-items: center; }
.chip-btn, .seg button {
  font: inherit; font-size: 0.875rem; color: var(--ink);
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 999px; padding: 6px 12px; cursor: pointer; min-height: 36px;
}
.chip-btn:hover, .seg button:hover { background: var(--surface-2); }
.seg { display: inline-flex; border: 1px solid var(--border); border-radius: 999px; overflow: hidden; background: var(--surface); }
.seg button { border: 0; border-radius: 0; }
.seg button[aria-pressed="true"] { background: var(--cyan-wash); font-weight: 650; }

main { max-width: 1180px; margin: 0 auto; padding: 4px 20px 48px; }
.site-footer { max-width: 1180px; margin: 0 auto; padding: 24px 20px 40px; color: var(--ink-2); font-size: 0.875rem; }

.card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 18px;
}
.note {
  background: var(--note); border-radius: 10px; padding: 10px 12px; font-size: 0.9rem;
}

/* Tab bar (ARIA tabs), sticky under the header so another tool is one tap away. */
:root { --tabs-h: 54px; }
.tabbar {
  position: sticky; top: 0; z-index: 20; background: color-mix(in oklab, var(--page) 92%, transparent);
  backdrop-filter: blur(6px); border-bottom: 1px solid var(--hairline); margin-bottom: 10px;
}
.tabs { display: flex; gap: 4px; max-width: 1180px; margin: 0 auto; padding: 0 20px; }
.tabs [role="tab"] {
  flex: 0 1 auto; display: inline-flex; align-items: center; gap: 8px; min-height: var(--tabs-h);
  padding: 6px 14px 4px; color: var(--ink-2); text-decoration: none; font-weight: 600;
  border-bottom: 3px solid transparent; border-radius: 8px 8px 0 0;
}
.tabs [role="tab"]:hover { color: var(--ink); background: var(--surface-2); }
.tabs [role="tab"][aria-selected="true"] { color: var(--ink); border-bottom-color: var(--cyan); background: var(--surface); }
.tabs [role="tab"]:focus-visible { outline-offset: -3px; }
.tab-icon { flex: none; }
@media (max-width: 560px) {
  :root { --tabs-h: 58px; }
  .tabs { padding: 0 4px; gap: 0; }
  .tabs [role="tab"] { flex: 1 1 0; flex-direction: column; gap: 2px; padding: 6px 1px 3px; font-size: 0.7rem; text-align: center; line-height: 1.15; min-width: 0; letter-spacing: -0.01em; hyphens: auto; }
  .tab-icon { width: 20px; height: 20px; }
}
@media (max-width: 380px) { .tabs [role="tab"] { font-size: 0.64rem; } }
@media (forced-colors: active) { .tabs [role="tab"][aria-selected="true"] { border-bottom-color: Highlight; } }
[role="tabpanel"]:focus { outline: none; }
[role="tabpanel"] [id] { scroll-margin-top: calc(var(--tabs-h) + 12px); }
.tab-loading { color: var(--ink-2); padding: 40px 0; }
.is-target { outline: 2px solid var(--cyan); outline-offset: 2px; border-radius: 6px; }
.sources li.is-target { background: var(--note); outline: none; }
h1 { background: linear-gradient(90deg, var(--green-ink), var(--cyan-strong)); -webkit-background-clip: text; background-clip: text; color: transparent; }
@media (forced-colors: active) { h1 { color: CanvasText; background: none; } }

/* Calculator pages */
.tool-cols { display: grid; gap: 18px; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); align-items: start; margin-top: 14px; }
.tool-cols .wide { grid-column: 1 / -1; }
@media (max-width: 880px) { .tool-cols { grid-template-columns: minmax(0, 1fr); } }
.fields { display: grid; gap: 10px 14px; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); }
.field label { display: block; font-size: 0.85rem; font-weight: 600; color: var(--ink-2); margin-bottom: 3px; }
.field-in { position: relative; display: flex; align-items: center; }
.field-in input, .field-in select {
  width: 100%; font: inherit; padding: 8px 10px; border-radius: 9px; border: 1px solid var(--border);
  background: var(--surface); color: var(--ink); min-height: 42px; font-variant-numeric: tabular-nums;
}
.field-in input[aria-invalid="true"] { border-color: var(--danger); box-shadow: 0 0 0 1px var(--danger); }
.field-in .unit { position: absolute; right: 10px; color: var(--ink-2); font-size: 0.85rem; pointer-events: none; }
.field-in input:has(+ .unit) { padding-right: 3.6em; }
.hint { font-size: 0.8rem; color: var(--ink-2); margin: 3px 0 0; }
.card h2 .step { display: inline-grid; place-items: center; width: 1.6em; height: 1.6em; border-radius: 50%; background: var(--cyan-wash); color: var(--ink); font-size: 0.85em; margin-right: 6px; }
.sub { color: var(--ink-2); margin: 0 0 8px; }
.kv { width: 100%; border-collapse: collapse; font-size: 0.9rem; }
.kv th, .kv td { text-align: left; padding: 5px 4px; border-bottom: 1px solid var(--hairline); vertical-align: top; }
.kv td.v { text-align: right; font-variant-numeric: tabular-nums; white-space: nowrap; }
.kv td.eq { color: var(--ink-2); font-size: 0.8rem; white-space: nowrap; }
.err { color: var(--danger); font-size: 0.9rem; min-height: 1.2em; margin: 6px 0 0; }
.facts { margin: 0; display: grid; gap: 10px; }
.facts dt { font-weight: 650; font-size: 0.92rem; }
.facts dd { margin: 2px 0 0; }
.src { font-size: 0.78rem; vertical-align: super; line-height: 0; text-decoration: none; margin-left: 1px; }
.sources ol { padding-left: 1.4em; margin: 0; display: grid; gap: 6px; font-size: 0.9rem; }
.sources li { overflow-wrap: anywhere; }
.nav-tools { display: flex; gap: 10px; flex-wrap: wrap; font-size: 0.9rem; }
.nav-tools a { text-decoration: none; color: var(--ink-2); padding: 4px 2px; }
.nav-tools a[aria-current="page"] { color: var(--ink); font-weight: 650; border-bottom: 2px solid var(--cyan); }
.fields .field.select { grid-column: span 2; }

details.more { margin-top: 12px; border-top: 1px solid var(--hairline); padding-top: 10px; }
details.more > summary { cursor: pointer; font-weight: 650; color: var(--green-ink); }
.field-label { display: block; font-size: 0.85rem; font-weight: 600; color: var(--ink-2); margin-bottom: 3px; }